This chapter presents an overview of current and forthcoming access network technologies and how they are likely to be deployed in access networks around the globe. These technologies are discussed in the light of commercial considerations, such as the current market structure, the impact of competition and regulation, as well as the demand for new broadband and Internet services.

The DSL technologies outlined in this chapter are still evolving. Each new generation brings improvements in functionality, performance and levels of integration. This trend of technology development and innovation looks set to continue, in the same way that voiceband modems evolved to exploit the capacity of the voice channel more efficiently. The fact that VDSL occupies frequencies up to 12 MHz, implies that further innovation in DSL transmission will arise in large part by exploiting multi-pair transmission, and by reducing the distance between the customer and the network provider. VDSL is the first DSL technology to be designed from the outset to be operated remotely from the local exchange to provide high throughput transmission. Since the key limitation to DSL capacity is crosstalk, BT has invested considerable effort in understanding the crosstalk environment of its network. This measurement and modelling effort is enabling the real-world performance of new DSL systems to be quantified, which in turn helps a Telco like BT to work with its suppliers to optimise system designs. It also facilitates more accurate performance predictions and equipment deployment rules. In summary, the Telco-installed copper-pair network presents a challenging and hostile environment for high-speed, multi-megabit/s transmission. However, realisation of the megabit capacity of the existing network is critically dependent on understanding and controlling the crosstalk environment to ensure spectral compatibility for new and legacy xDSL transmission systems.

Broadband has been much talked about in terms of its impact on industry and the home. We know that the government believes broadband is important to the prosperity of the country through the push for a Broadband Britain. But it is far from a simple subject and there is much that has been said either to make a particular point or simply in error There are many players in the story, and the range of products offered is very broad. This chapter provides a worked example of the introduction of DSL-based broadband services. It starts by looking at the definition of broadband, correcting some of the myths that have been circulated, and discusses the range of technologies available to deliver broadband. It then focuses in on the DSL story so far with a look at the technology and a short history of the evolution of broadband. It looks at the players in the broadband business model before outlining the broadband products offered by BT and the design of the solution that supports those products. The chapter concludes by commenting on the early experience, drawing comparisons with others and considering some of the possible evolutions of the DSL broadband story.

Local loop unbundling (LLU) is a regulatory device that allows telecom operators without physical network infrastructure to lease access to the physical assets of other operators. It is called unbundling as it reverses the normal 'bundling' process whereby network owners usually only sell telecom services to customers in bundles which consist of switching, transmission, billing as well as the use of the physical infrastructure. There has been much discussion of LLU recently as telecom regulators, mainly in the USA and Europe have introduced it in an attempt to boost competition in local access services and broadband access in particular Much of the discussion has focussed on LLU from the new entrant operator perspective. This chapter describes the implementation of LLU from the incumbent operators perspective. The authors have all been key members of the team that introduced LLU services to BT. The experience described here although based on BT and the UK regulations will be of general interest and application to other countries and other operators.

Optical fibre access network technology has become more complex over the last few years with bit rates steadily increasing. PON systems are available with bit rates in the range 155Mbit/s to, currently, 622Mbit/s. Newer systems, both PON and point-to-point, will allow this trend to continue with 2.5 Gbit/s systems becoming practicable in the near future. With this increase in technology has come an increase in the opportunities for fibre system to cost-reduce more of the network, including the metro space a fact that increases the appeal of the technology. Some of the newer PON systems are being designed using Ethernet as the underlying technology with a promise of reducing the price of the technology still further. How this will occur in practice, however, is still unclear. What is certain is that optical access technologies are expanding and are sure to find an opening in real networks in the foreseeable future.

Mankind has been communicating via radio signals for a very long time, between neighbouring buildings, across oceans and even from one planet to another Theoretically such technology can be used for the last mile of a telecommunications network to connect its customers. In practice, however, it is not well suited to such use and it is only over the last decade or two that tailored solutions have emerged, allowing large scale wireless access to become economically viable. Wireless access splits into two classes fixed and mobile. Fixed systems are known by many names including fixed wireless access (FWA), wireless local loop (WLL), multimedia wireless systems (MWS), broadband wireless access (BWA) and local multipoint distribution systems (LMDS). While mobile systems allow users to roam around the network, in fixed systems the radio units are permanently mounted in the same way as copper and optical fibre. Using radio in the access network presents a unique set of engineering challenges, especially if service quality is to rival wired delivery. Securing suitable spectrum is a prerequisite to establishing a network. The transmission medium presents many challenges which are outside the direct control of the network operator, and those that are of particular importance for fixed applications have to be considered when selecting radio equipment. Careful planning of the network is required to ensure it meets initial and longer term market requirements and the initial technology and architecture choices are key to achieving success. When all these aspects have been considered, a network operator can assess the likely costs and revenue of a wireless system and can answer a more fundamental question is wireless the best choice of access technology for this application? This chapter will explore each of these issues in more depth.

This chapter addresses the access capabilities of satellite. It does not go into depth on the more traditional services that satellite have been associated with, except as an initial positioning statement. It then goes on to describe the options for access, performance of IP services over a satellite path, discusses emerging technology that will impact on future service delivery, presents information on regulatory and spectrum aspects and closes with an brief overview of standards activities.

In this chapter we describe the key components of a cable TV system that enable these homes to receive voice. TV and broadband (and thus more voice and more and more video applications) over this single media. This integration is the attraction for the end users. The cable industry, as opposed to the DSL industry for example, has a much more standard-based approach that is closely driven by service providers and vendors alike. The notorious DOCSIS protocol, for example, revolutionised the cable industry by providing interoperability between vendors and delivering high speed data services over the cable TV infrastructure. In this chapter, we describe the various components of a broadband and voice-enabled cable infrastructure and discuss the key standards in use and forthcoming in this market place.

This chapter considers the deployment of network management systems to support the access network. It considers some of the key drivers for the integration of network management systems (NMS) and discusses the technology and standards that can be used to achieve this integration. A brief tutorial on the Telecommunication Management Network (TMN) standards is given. The chapter goes on to consider an example of a managed network and some of the implementation aspects of introducing TMN systems.